Pneumatic driving hammers



J. A. M. DELVAUX 2,787,123

4 Shets-Sheet 2 PNEUMATIC DRIVING HAMMERS A ril 2, 1957 Filed -lvlarch23, 1954 April 9 J. M. DELVAUX 2,787,123

PNEUMATIC DRIVING HAMMERS Filed March 23, 1954 4 Sheets-Sheet 3 a Q JApril 2, 1957 J. A. M.- DELVAUX 2,787,123

PNEUMATIC DRIVING HAMMERS Fild March 23. 1954 4 Sheets-Sheet 4 PNEUMATICDRIVENG HAMMERS Jules Arnold Marie D'elvaux, Tilleur, Belgium, assignorto Compagnie Internationale des Pienx Armes Frankignoel, SecieteAnbnyme, Liege, Belgium Application March 23;.1'954,.Serial No. 418,128Claims priority, application France March 25, 1953 15 Claims. (C160--57) The present invention relates to pheumatic driving hammers whichare particularly suitable for driving in piles, sheet-piling and thelike, although it is by no means limited to such applications.

The object of the invention is toprovide a pneumatic hammer enabling alarge striking power to be developed notwithstanding that the strikingmass is of relatively low weight, in which, moreover, the striking powerand the impact velocity are capable of variation over wide limits withthe use of simple means. The advantage of this is that the sameapparatus may be used for different kinds of operations, requiring verydifferent striking powers, so that a single" apparatus according to theinvention is capable of replacing a whole range of theusualtypes ofautomatic hammers.

For pile driving and similar operations, this is an advantage of someimportance since the penetrating force due to the impact may be adaptedto the medium which has to be traversed.

The pneumatic hammer according to the invention therefore comprises astriking mass guided with a reciprocating motion in a casing, an aircylinder being formed in one of these elements so as to coact with apiston solidly connected to the other ofthese elements, means beingprovided for raising the striking mass while compressing the air insides'aid cylinder and for releasing the mass in question after a givenup=stro'ke in order to give rise to the striking motion of said massunder the combined action of its own weight and the expansion of the aircompressed in said cylinder, means being provided for regulating theinitial pressure of the air inside this cylinder at the commencement ofthe lifting motion of the striking mass to any value between atmosphericpressure and some arbitrarily determined higher pressure.

The compressed air used for imparting the desired speed of impact to thestriking mass is thus able to exert its expansion between two adjustablepressure limits, this making it possible to modify at will the work ofexpansion and the rate of the residual pressure prevailing in the aircylinder at the end of the expansion and which maintains the strikingmass on the object of the impact with a static force of adjustableintensity, enabling an impact of lingering type to be obtained, or, inother Words, this static force opposes the rebounding of the strikingmass and holds it in position after each nited States Patent drop untilthe next lifting motion. This lingering type of impact, hitherto unknownin any of the known systems, provides a very eflective transmission ofthe kinetic force of the striking mass to the object under the impact.

According to another feature of the invention, the said initial airpressure may be supplied by an air pumpcontaining a cylinder and apiston, one of these members being formed by the striking mass and theother by a member integral with the casing, the cylinder of the pumpbeing connected to the atmosphere through a passage provided with acheck valveopening towards the cylinder and to the said air cylinderthrough a passage 2,787,123 Fatented Apr. l2, 1957 provided with a checkvalve opening towards the air cylinder, the air cylinder beingconnected. to the atmosphere by a passage provided with a safety valveopening under the action of a given adjustable pressure, the said pumpbeing of such a construction that its compression ratio is greater thanthe compression ratio obtained in said air cylinder.-

This safety valve will limit, to a value corresponding to the forcenecessary for opening valve, the final pressure reached in the aircylinder at the end of the compression stroke, that is, atthe end of thelifting motion of the striking mass, andsince the compression ratio inthis cylinder is known, it will likewise determine the final expansionpressure, that is, the initial pressure for the next compression. Allthat isrequired therefore is to modify the resistance to opening of thesafety valve in order to modify the initial pressure and the endcompression pressure in the air cylinder or the value of the strikingpower of the hammer which depends on these pressures. The velocity ofthe blow of the hammer will be modified at the same time a's i t isdependent on the intensity of the expansion in the air cylinder.

Likewise, in accordance with the invention, the means provided forraising the striking mass and releasing it at the end of the liftingstroke may advantageously consist of a hydraulic motor containing. acylinder. integral with the casing and a piston to which areciprocatingmotion is imparted under the action of. the driving liquid, the rod ofthe piston being connected to the striking mass by a locking mechanismso that the mass in question is carried along by said piston when itrises inside its cylinder under the action of the liquid under pressuresupplied under the piston, while at leastone member coac ting with anabutment forming part of: the: cylinder releases the said lockingarrangement and. frees the striking mass at the end of the upward travelof. the piston, the rod of this piston being again automaticallyconnected to the :said mass when the locking mechanism engages in itagain atthe end of the down travel of the hydraulic piston.

Finally, mechanical means are provided according to the invention forraising the striking mass and releasing it at the end of the tip-stroke.

One embodiment of thepresent invention is described hereinafter withreference to the accompanying drawings, a number of constructionaldetails which are not needed in order to understandthe invention being.left out.

Fig. 1 is a longitudinal sectional View of apneumatic hammer accordingto the invention taken on the polygonal line 1-1 of Fig; 5, when thestriking. mass is at the bottom of its stroke, at the starting momentofthe upstroke. x

Fig. 2 represents a similar view taken slightly before the end of theLip-stroke at the start of the disengagement of the locking means.

Fig. 3 is a similar view with a; locking means disengaged at the end ofthe upstroke of the mass.

Fig. 4 is a partial similar view slightly before the end of thedown-stroke of the hydraulic piston at the start of the engagement ofthe locking means.

Fig. 5 is a cross-sectional view taken on the line V-V of Fig. 3.

Fig. 6 is a part sectional: view of a: modification, the striking massapproaching the end of its upward stroke.

Fig. 7 is a; complete view, with partsinsection, of the hammer with thecontrol arrangement of the distributor, the hydraulic distributor,- thehingedl y arranged pipe and the pump supplying the hammer with liquidunder pressure.

Fig. 8 shows a mechanical system for raisingthe strikmg mass.

As shown more particularly in Figs. 1 to 5, the hammer comprises acasing 1 which is of square cross-section in the example illustrated,provided with a cover 2 and a bottom part 3 acting as the anvil, thesethree elements being connected together by four tie rods 4 extendingbetween the cover 2 and the bottom 3 at the corners of the casing 1. Forreasons of clarity only the top part of the right-hand tie rod has beenshown in Fig. 1. Dogs 5 project underneath the bottom part 3 and areused for example for centering the hammer on the head of a pile or thelike.

The striking mass which is cylindrical externally is provided with anunder frusto-conical shaped part 6 and an upper cylindrical part 7,these two parts being connected together with a mating ridge 8 andscrews, not shown, with the heads embedded inside recesses in the base6. The mass 6, 7 is guided by eight outer guide sleeves 9 embracing thetie rods 4, four of these sleeves being arranged at the top part andfour of them at the lower part of the said mass. The latter is providedwith a central cylindrical hollow part 10 embracing a piston 11 formedby the enlarged end of a cylinder 12, the whole of the latter unit beingsecured to the cover 2 by means of tie rods 13.

Twelve radial openings 14 are provided in the lower part of the wall ofthe cylinder 10. Eleven of these openings open into closed cylindricalcavities 15 formed in the thickness of the member 7 and serving asclearance space. The twelfth opening 14 opens into a passage 16 leadingto an air pump cylinder 17 in the body 7 parallel to the cylinder 10. Acheck valve 18 opens towards the cylinder 10 and is arranged in thepassage 16, the latter being able to communicate with the atmospherethrough a safety valve 19 loaded by means of an adjustable tensionspring. The detail of this valve has not been shown in Figs. 2 to 4. Itconsists for example of a ball under the action of a pressure springfitted inside a cup screwing into a fixed recess, the tension of thespring being adjusted by screwing the cup in question in or out. Inorder to facilitate this operation a port 19' may be provided in thecasing 1 opposite the said cup member when the striking mass is in theposition illustrated in Fig. 1.

An air pump piston 20, shown half of it in section, and the other halfas an outer view, is provided with packing and engages in the cylinder17 and is fixed to the cover 2 by means of the rod 21. A check valve 22opening towards the cylinder 17 is provided in the piston 20.

A piston 23 provided with packing and integral with a rod 24 engages thecylinder 12, the top end of which is connected to the distributor 53,Fig. 7, by means of a pipe line 55. The rod 24 is guided in the centralopening formed in the piston 11 and provided with packing rings, thediameter of the opening in question being smaller than that of the boreof the cylinder 12. Four radial bores 26 are provided in the body of thepiston 11 and are connected to pipes 27 connected with the distributor53, shown in Fig. 7. The rod 24 is provided at its other end with acylindrical foot 28 able to engage in a cavity 29 (Fig. 4) ofcorresponding shape formed in the upper face of the base 6 of thestriking mass. The foot 28 is provided with a system for attaching themass 6, 7 to the rod 24, this system consisting of two catches 30slidingly mounted inside diametrically opposite horizontal recessesformed inside the foot 28. The ends of these catches 30 are beak-shapedhaving an upper horizontal face and a lower inclined face, theinclination of which corresponds to that of an opened out part at theupper edge of the cavity 29. Two tension springs push out the catchestowards the outside, their projecting position being limited by theabutments 31 (Fig. 1). In each of the catches mentioned there is amortise 32 provided with an inclined plane. Two push elements 33projecting from the top face of the foot 28 are slidingly mounted insidevertical recesses formed in the said foot and in the same axis as themortises 32, these push elements terminating in a bevel part whichcoincides with the inclined plane of the corresponding mortise. Springs34 normally maintain the push members in the position. shown in Fig. 1.There is a cavity 35 formed in the lateral wall of the cavity 29 toserve as a catch for the catches 3% when the foot 28 is engaged in thiscavity 29.

Holes 36 are provided in the casing 1 so that there will be atmosphericpressure in the casing all round the striking mass 6, 7 above the piston20.

The whole apparatus can be moved around easily by means of an eye bolt37 fixed on the cover 2.

The pneumatic hammer described works in the following manner:

On starting, all the members are situated in the position shown in Fig.1, the striking mass 6, 7 being attached to the foot 28 integral withthe rod 24 of the piston 23 by the catches 30 engaging in the cavity 35.The piston 20 of the air pump occupies the position at the end of theup-stroke.

Oil under pressure, supplied by an auxiliary pump 50 shown in Fig. 7,arrives through the pipe line 27 and the bores 26 into the cylinder 12,under the piston 23, causing it to rise taking with it the mass 6, 7. Atthe commencement of the first up-stroke, the air inside the cylinder 17of the pump and the air cylinder 10 with its clearance spaces 15 is atatmospheric pressure. The check valve 22 is closed during the up-strokeand the air is compressed in the spaces 10, 15, 17. The respectiveclearance spaces of the pump cylinder 17 and of the air cylinder 10being proportioned in such a manner that the compression ratio is muchgreater in the pump cylinder than in the air cylinder, the pressureincreases more rapidly inside the cylinder 17 and opens the check valve18 so that air is delivered from the cylinder 17 into the cylinder 10through the passage 16 and the corresponding opening 14.

Towards the end of the up-stroke, shown in Fig. 2, the push elements 33come against the under face of the piston 11 and descend in the foot 28of the rod 24, their end bevels coacting with the inclined faces of themortises 32 and causing the catches 30 to enter their recesses. Thisretraction of the catches 3t) releases the striking mass 6, 7 which ispropelled downwards on to the anvil 3 under the combined action of itsown weight and the expansion of the compressed air in the cylinder 10and the clearance spaces 15.

The check valve 18 closes at the end of the compression. The air in thecylinder 10 and in the clearance spaces 15 expands during the whole ofthe descent of the striking mass.

Inside the cylinder 17 of the air pump there is first of all anexpansion of the air remaining in it and as soon as this air has reachedsub-atmospheric pressure the valve 22 opens and lets air in from theoutside so that at the end of the down-stroke of the striking mass, thecylinder 17 is again filled with air at atmospheric pressure. 7 Afterthe release of the striking mass, when the piston 2? has reached the topof the up-stroke, the distributor interrupts the supply of liquid underthe piston 23 and delivers the liquid under pressure to the top face ofthe piston through the pipe line 55, shown in Fig. 7. The piston 23descends under the action of the pressure of the oil and the weight ofthe moving elements Z3, Z4, 28 and forces the oil through the piping 27.At the bcginning of this down-stroke, the springs 34 move the pushelements 33 back into their initial position and free the catches (it)so that they are forced outwards by their springs. Towards the end ofthe stroke, the catches encounter the inclined edge of the opening 29 asshown in Fig. 4, so that they are forced into their recesses until theyfind themselves opposite the cavity 35 into which they engage under theaction of their springs, so that the mass 6, 7 is attached once more tothe piston 23 and the unit is again in the position shown in Fig. 1ready for another ascent of the striking mass, the oil pressure being inthe meantime re-established in the piping 27.

sesame The initial pressure inside the air cylinder is however alreadygreater than atmospheric pressure on accourit of the supplementaryquantity of air which has been introduced into it by the pump 17, sothat the final compression pressure will be increased as a result. Ateach cycle, the initial pressure and the final compression pressureinside the cylinder iii and the clearance spaces 15 will be increaseduntil the final pressure has reached the value determined by theregulation of the safety valve.

This normal working pressure is reached after a numher of cycles whichis a function of the value of this pressure and from this moment, thepump is only used to compensate losses in order to keep the workingpressure at the desired value. The air surplus delivered by the pumpwill be evacuated by the valve 19. The residual pressure inside thecylinder it? after each expansion exercises a static force on the mass6, 7 and provides the lingering impact. This pressure may be determinedat will and it may be modified according to requirements, by regulatingthe valve 19. Of course, a set of interchangeable valves 19 might beused each provided with a spring of different strength but it is simplerto use a valve the pressure of which is adjustable than to replace thevalve.

It will be noted that the apparatus does not require the use of steam orcompressed air to be supplied by a separate generator. This helps toprevent any disturbance in the working which frequently takes place withcompressed air apparatus on account of small losses which arepractically unavoidable. The hydraulic system de scribed for raising thestriking mass may be replaced by any suitable form of actuatingarrangement such as for example an electric arrangement or a mechanicalarrangement, and example of which will be descibed hereinafter withreference to Fig. 8.

In Fig. 6 is shown another system of attaching the striking mass. Inthis case, the foot 33 of the rod 24 comprises two diametricallyopposite recesses in which are arranged two hooks 39 able to oscillatethrough the medium of ball or roller hearings on two pivots 49 fixed inthe foot and passing through the recesses formed in the latter. Twotension springs 43. situated on either side of the rod 24 are attachedto extensions 42 of the hooks above the pivots 4! These springstherefore have a tendency to force the lower beaks of the hooks 39towards the outside.

in its upper face the mass 6 is provided with a central cavity insidewhich extend two pins 43 mounted on ball or roller hearings in saidmass. Two parts id; each forming an inclined surface 45 above a pin 43are fixed the two abutments 47, these being provided for cooperatingwith heels 43 on the hooks 39 and being mounted with shock absorbersconsisting for example of a series of Belleville rings 49.

The mass 6, 7 is shown in Fig. 6, attached to the rod 24, at the momentwhen it is about to be released at about the end of the tip-stroke. Theheels 48 of. the hooks come into contact with the abutments- 47 and rockthe hooks on the pivots while the rod 24 con tinues its upward motion.The beaks of the hooks roll over the pins 43 and escape from them, atthe same time releasing the mass 6, 7 and reassume the positionillustrated under the action of the springs 41.

After the descent of the striking mass, the rod 24 redescends, the beaksof the hooks meeting the inclined surfaces and being moved to the insideagainst the action of the springs 41, then sliding over the pins 43 andhooking finally under them. In this way, the mass 6, 7 is again attachedto the rod 24 and follows the latter during its up-motion.

Fig. 7 shows a hydraulic control arrangement for proseeing thereciprocating runner: of the red some head 286d this rod being providedwith a device of s'orr're forin for attaching the mass 6, '7. The li uidunder pressure is supplied by a pump 50 driven by an electric motor orother driving means. The motor-pump unit isrriounted on an independentchassis or on the platform of the machine to which the hammer issuspended. The pump is connected to the hammer by means of a. doublearticulated piping Si, 52, this being necessary through the displacementof the hammer as the pile, sheetpile or the like is driven in. Thesepipes, or the suction and delivery respectively of the pump, areconnected to the distributor 53 situated inside a recess surmounting thecover 2 and connected by a pipe 27 to the lower part of the cylinder 12and with a pipe 55 to the upper part of the same cylinder. Thedistributor is controlled by a push element 56 sliding inside a sleeve57 and provided at its lower part with a double abutment 58, 59 arrangedinside a central hollow part 60 of the rod 24:

When the liquid under pressure is delivered through pipe 2'7 under thepiston 23, the latter rises until the bottom of the hollow part 60encounters the abutment 59 and displaces the push element 56 controllingthe distributor 5;. and interrupting the supply through the pipe 27 andsupplying the liquid under pressure through the pipe 55 to the top ofthe piston 23, the liquid situated under the piston escaping backthrough the pipe 27. At about the end of the descent of the piston, theupper wall of the hollow part 60' meets the abutment 58 and takes thepush element 56 along with it so as to reverse the distributor, thelatter then delivering liquid under pressure once more under the pistonto produce a new tip-stroke of the rod 24.

As shown in Fig. 8; the rod may also be driven mechanically. The rod 24is provided with a head 61 provided with shoes sliding inside a guide 62fixed to the cover 2 of the pneumatic hammer. This head is connected toa connecting rod 63 passing freely through this cover and provided witha to and fro motion by a mechanism inside a casing fixed to the cover 2.In the example, this mechanism comprises a motor 64, of electr'ical oranother type, which actuates through a set of bevel gears 65 and someform of reduction gear 66 a crankshaft 67 to the pin of which isconnected the end of the rod 63.

I claim:

1. A pneumatic driving hammer, particularly suitable for driving piles,sheet-piling and the like, comprising. a casing; open to the atmosphere,the base of said casing forming an anvil, a striking mass guided with areciproeating motion therein, anair cylinder and piston assembly, aportion of said air cylinder and piston assembly being formed by saidstriking mass, another portion of said air cylinder and piston assemblybeing connected to said casing, first means for raising the strikingmass and thereby compressing air contained in said air cylinder, saidfirst means freeing said striking mass after a given raising of saidstriking mass so as to produce a striking motion of said striking massunder the combined action of the weight of said striking mass and theexpansion of the air compressed inside said air cylinder, and secondmeans for establishing an initial pressure of air above atmosphericpressure inside said air cylinder at the start of the upward movement ofthe striking mass;

2. A pneumatic hammer as claimed in claim 1, including a pneumatic pumpfor producing the initial pressure and having a compression ratiogreater than that in said air cylinder, said pump consisting of a pumpcylinder and pump piston assembly, a portion of said pump cylinder andpump piston assembly being formed by the striking mass, another portionof said pump cylinder and pump piston assembly being formed integralwith said casing, a passage connecting said pump cylinder with theatmosphere, a check valve arranged in said passage and opening towardssaid pump cylinder, a second passage connecting the pump cylinder withsaid air cylinder, at check valve arranged in said second passage andopening towards said air cylinder, and a safety valve connecting saidair cylinder with the atmosphere and having a resistance to openingcorresponding to the maximum pressure to be reached in said air,cylinder.

3. A pneumatic hammer as claimed in claim 2, in which means are providedfor adjusting the resistance to opening of said safety valve.

4. A pneumatic hammer as claimed in claim 1 in which said air cylinderpermanently communicates with a clearance space formed outside said aircylinder.

5. A pneumatic hammer particularly suitable for driving piles,sheet-piles and the like comprising a casing, a prismatic shell thereof,a bottom forming an anvil and a cover connected to said bottom by meansof longitudinal tie rods, a striking mass mounted for reciprocatingmotion in said casing, an air cylinder formed by a hollow central partof said striking mass, a pump cylinder formed from the upper face insaid mass at the side of said hollow central part, a passage connectingthe bottom ends of said pump and air cylinders, a check valve arrangedin said passage and opening towards said air cylinder, closed cavitiesformed in said mass around said air cylinder and communicating with thebottom end of said air cylinder, a piston integral with said cover andengaging in said air cylinder, a piston integral with the cover andengaging with said pump cylinder, a check valve in said latter pistonopening towards said pump cylinder, a safety valve connected with thepassage joining said cylinders and opening to the atmosphere, guidemeans for the striking mass in said casing, openings provided in thelatter and opening to the atmosphere, and means for raising the strikingmass and for freeing said mass after a given up-stroke.

6. A pneumatic hammer as claimed in claim 5, in which said guide meansinclude members integral with said striking mass and slidingly mountedon said tie rods.

7. A pneumatic hammer as claimed in claim 1, in which the means forraising the striking mass and freeing it at the end of the up-strokecomprise a rod slidingly mounted in the hollow central part of thepneumatic hammer and passing in sealed and guided manner upwardly out ofthe air cylinder, a motor provided for acting on the upper end of saidrod and imparting to it a to and fro motion, the rod being also providedwith an enlarged foot formed at the lower end of said rod and providedwith an automatic attachment mechanism for connecting the rod to saidstriking mass at the end of the down movement imparted to said rod bysaid motor, and at least one member supported by the rod for coactingwith an abutment integral with the casing for releasing said attachmentmechanism at the end the up-stroke of the said rod.

8. A pneumatic hammer as claimed in claim 7, in which the motor actingon the upper end of the said rod is a hydraulic motor, including acylinder formed by a hollow central part of the piston of the aircylinder, and an enlarged head being formed on said rod for forming thepiston of the hydraulic motor.

9. A pneumatic hammer as claimed in claim 8, including means foralternately introducing driving liquid to the bottom and top faces ofthe hydraulic piston, and for simultaneously evacuating the liquid fromabove, respectively below said piston.

10. A pneumatic hammer as claimed in claim 8, including pipes forpassing liquid which open into the bot tom end and into the top end ofthe hydraulic cylinder respectively, a distributor mounted on thepneumatic hammer and connecting these pipes to the suction and deliverypipelines respectively of a hydraulic pump and means for actuating thisdistributor and thereby changing the connections between these pipes andpipe lines at the end of each stroke of the hydraulic piston.

11. A pneumatic hammer as claimed in claim 10, in which the means foractuating the distributor include a push element traversing thehydraulic cylinder and having its lower end penetrating into a centralcavity formed in said rod, and two abutments provided on said pushelement for coacting with the upper wall and with the bottom wall of thesaid central cavity respectively.

12. A pneumatic hammer as claimed in claim 7, in which the upper end ofthe said rod is guided axially inside a hollow part of the pneumaticpiston and open to atmosphere, the motor acting on said upper endincluding a connecting-rod connected to said upper end and passingfreely upwards out of said hollow part, the connecting rod being alsoconnected to a mechanical drive system mounted on the hammer andimparting a to-andfro motion to the connecting-rod.

13. A pneumatic hammer as claimed in claim 7, including a central cavityformed in the bottom of the air cylinder for receiving the enlargedfoot, horizontal recesses formed in the enlarged foot, catch elementswith beak-shaped outer ends slidably mounted in said recesses, springsacting on said elements for forcing them towards the outside so that thebeak-shaped ends project laterally, a recess provided in the lateralwall of said cavity for receiving said beak-shaped ends to attach thesaid rod to the striking mass, push elements provided with beveled lowerends mounted vertically in sliding manner in said foot, a mortise havingan inclined inner lateral face in each of said catches opposite one ofsaid push elements, so that when the push elements, abutting against thepneumatic piston at the end of the up-stroke, are forced into said footagainst spring action, they push the said catches into their recessesand so release the foot from the said striking mass.

14. A pneumatic hammer as claimed in claim 7, including two hooksmounted in rocking manner on pivots carried by the said foot pinssupported by the striking mass for coacting with said hooks, springsacting on the hooks for displacing them in a direction corresponding totheir attachment to the pins of the striking mass, upper extensionsprovided on these hooks, abutments provided on the bottom face of thepiston of the air cylinder for coacting with said extensions at the endof the upstroke of said rod and thereby displacing the hooks against theaction of said springs.

15. A pneumatic hammer as claimed in claim 14, in which the saidabutments are resilient.

References Cited in the file of this patent UNITED STATES PATENTS858,322 Bandimere June 25, 1907 1,320,688 Healy Nov. 4, 1919 1,380,072Miller May 31, 1921

